This section introduces aspects that may help facilitate a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is prior art or what is not prior art.
Operators deploying LTE often have several different frequency bands at their disposal, for example 700 MHz and the 2100 MHz Downlink/1700 MHz Uplink band (referred to as the Advanced Wireless Services (AWS) band in the United States. An operator would be interested in deploying full nationwide coverage on the lower carrier frequency due to its better propagation characteristics, hence requiring fewer cell sites. However, as spectrum at the higher frequencies becomes available for LTE, the operator would be interested in deploying a 1:1 overlay on top of the lower frequency network, so as to avoid adding extra cell sites. The higher carrier frequency will have reduced coverage compared to the lower carrier frequency, meaning users who connect to the higher carrier frequency will experience very low data rates at the edge of the cell. Given that LTE is meant to provide high data rates over the entire cell coverage area so as to enable a new set of applications to be used (e.g., video calling), a simple 1:1 overlay may not meet the requirements of the operator.
One feature being developed as part of LTE Release-10 is the ability to support carrier aggregation (CA), which is the ability to aggregate 2 or more LTE carriers (called component carriers) together to form one large effective carrier, even if the carriers are in different frequency bands. The mobile devices will be able to simultaneously receive data and control signaling as well as make measurements on multiple component carriers on the downlink, as well as transmit on multiple component carriers simultaneously. The use of carrier aggregation can provide a performance benefit, but it also implies a significant increase in the complexity of the schedulers at the base station, for both uplink and downlink.
Thus, new solutions and techniques that are able to address one or more of the issues encountered in multicarrier systems would meet a need and advance wireless communications generally.
Specific embodiments of the present invention are disclosed below with reference to FIGS. 1-5. Both the description and the illustrations have been drafted with the intent to enhance understanding. For example, the dimensions of some of the figure elements may be exaggerated relative to other elements, and well-known elements that are beneficial or even necessary to a commercially successful implementation may not be depicted so that a less obstructed and a more clear presentation of embodiments may be achieved. In addition, although the logic flow diagrams above are described and shown with reference to specific steps performed in a specific order, some of these steps may be omitted or some of these steps may be combined, sub-divided, or reordered without departing from the scope of the claims. Thus, unless specifically indicated, the order and grouping of steps is not a limitation of other embodiments that may lie within the scope of the claims.
Simplicity and clarity in both illustration and description are sought to effectively enable a person of skill in the art to make, use, and best practice the present invention in view of what is already known in the art. One of skill in the art will appreciate that various modifications and changes may be made to the specific embodiments described below without departing from the spirit and scope of the present invention. Thus, the specification and drawings are to be regarded as illustrative and exemplary rather than restrictive or all-encompassing, and all such modifications to the specific embodiments described below are intended to be included within the scope of the present invention.